Hi Kevin,
We tested a similar case with 200000 line series, but removed the data labels and the legend. It took about one minute for the chart to render (most of the time is actually spent in object creation).
The chart allocated more than a gigabyte, but obviously this is not enough for an "out of memory" exception.
It looks that the text measurement and rendering in the legend takes a lot of time, which causes the chart to "hang" when the legend is visible.
Best Regards,
Nevron Support Team